It’s just a learning thing. If you sit the first time in a car, you’re overwhelmed by all the stuff you have to handle. When you get the mechanics down, they don’t need attention anymore and you can focus on other stuff until the point you drive casually while talking to someone and know where to focus to, as most things are now signals that are directly linked to information you don’t need to think about any more.
My tip is to focus on special things to improve until they are automated and don’t need your attention anymore. In time you have the basics down and you’re more free to actually think how to use the things automated rather how to do the things you’re thinking about.
Ps: true multitasking is a myth, we’re all single cores and slice our attention to fake it 